Rusinow leads is a bridge convention used as part of defensive carding. Rusinow leads are commonly used only on the opening lead against a suit contract; nevertheless, some experts use Rusinow leads only against notrump.
They were devised by Sydney Rusinow and used by him, Philip Abramsohn and Simon Rossant in the 1930s, but were banned until 1964 by the American Contract Bridge League.[1][self-published source][2]